Bone mineral density and vitamin D status in children with remission phase of steroid-sensitive nephrotic syndrome

Abstract

Children with idiopathic nephrotic syndrome are primarily treated with glucocorticoids (GCs), but long-term GC use can lead to undesired side effects. We investigated the bone mineral density (BMD) and 25-hydroxyvitamin D (25-OH D) levels in children with the remission phase of steroid-sensitive nephrotic syndrome (SSNS). This study included 32 patients with SSNS who had not received GC treatment in the last 6 months and a control group of 20 healthy children. Serum levels of calcium, phosphate, alkaline phosphatase, 25-(OH)D, and parathyroid hormone (PTH) were measured. BMD was determined in the lumbar spinal region using dual-energy X-ray absorptiometry (DEXA). Serum 25-(OH)D levels were lower in the SSNS patients than in the healthy children (P <0.05), with 22 patients (68.8%) having Z-scores <0.05). PTH levels were higher in patients with osteoporosis than in patients with Z-scores ≥-1 (P <0.05). Bone mineral content and BMD were positively correlated with the age of diagnosis (P <0.01). Receiver-operating characteristic curve analysis showed that the cutoff value of 25-(OH)D levels for predicting low BMD was 14.67 ng/mL with a sensitivity of 90% and a specificity of 64%. The area under the curve (AUC ± standard error) was 0.868 ± 0.064 (95% confidence interval: 0.742-0.994, P = 0.001). Decreased 25-(OH)D levels and the negative effects of long-term GC treatment on BMD persist in SSNS remission phase. Levels of 25-(OH)D <14.67 ng/mL could predict abnormal DEXA scans in children with SSNS remission phase.